Dough products, such as biscuit dough, are formulated and packaged in containers suitable for storage under refrigerated conditions. Because the dough exudes carbon dioxide during storage, accommodation must be made for pressure increases within the container during storage. Further, the dough also exudes greases and/or syrups that are degradative to paper, water-based glues, etc. Dough containers commonly are generally tubular, multilayered and comprise an inner layer, i.e. liner, that is in direct contact with the dough, a strength layer such as heavy paper, paperboard or cylinderboard and a label layer which is the outermost of the layers.
The prior art containers commonly are manufactured by serially helically winding the several layers about a cylindrical mandrel with the contiguous side edges of at least certain of the layers being bonded to one another to form an integral tube. This tube is finally cut into suitable lengths. U.S. Pat. Nos. 3,940,496 and 4,073,950, incorporated herein by reference, disclose methods for manufacturing such tubes. One end of each tube is sealed with a metal end cap as by swaging the periphery of the end cap to the tube to effect a seal therebetween. In one embodiment, the seal between the end cap and the tube wall is less than gas tight thereby leaving an escape route for gas exuding from the contained dough. This technique enables one to use a container of less burst strength (hence less costly). After the tubular container is filled with dough product, the opposite open end of the tube is closed and sealed in like manner using a further metal end cap. U.S. Pat. Nos. 3,506,183 and 4,235,341, incorporated herein by reference, disclose prior art helically wound dough containers. Commonly, in the lay-up of the layers of container, the contiguous side edges of the strength layers are abutting. This helical butt joint is held in place by a bond between the strength layer and the liner layer, plus a bond provided by an outer label layer which is peelable from the strength layer. By design, the label layer provides sufficient strength to the container to prevent the helical seal from rupturing until the label layer is peeled away whereupon the helical seal ruptures due to the pressure developed internally of the container. In some containers, opening of the containers by the consumer is most frequently accomplished by physically rupturing the helical seal as by striking the body of the container against a sharp corner of a kitchen cabinet or the like. Desirably, when using this procedure, the seal consistently ruptures at the point of impact of the container against the sharp edge.
Prior art liners for dough containers are known to include urea formaldehyde treated paper glue laminated to an aluminum foil as a gas and moisture barrier layer, which in turn is bonded to a very thin (e.g. about 1 lb/3MSF) polyvinyl chloride based heat seal coating, such coating serving to effect the bond between the contiguous edges of the helically wound web during layup of the liner in a helically wound configuration. Such prior art liners suffer from severe environmental problems. Specifically, the use of urea formaldehyde in papermaking results in free formaldehyde in the area of the papermaking machine, such formaldehyde being a potential health hazard to workers. Accordingly, it is required that protective measures be taken for such workers, such measures resulting in higher costs for production of the paper product. Further, urea formaldehyde-treated papers are difficult to use as a source product for the manufacture of recycled paper. Still further, the polyvinyl chloride of the prior art containers poses a prohibited chemical problem under certain state regulations, such as California Proposition 65, as being carcinogenic and/or a reproductive toxin. The incineration of containers containing polyvinyl chloride also generates HCl which is a purported source of acid rain. The present container liner is free of urea formaldehyde, polyvinyl chloride and similar potential environmental hazards.